Apparatus and method for manufacturing a semiconductor device having hemispherical grains

ABSTRACT

An apparatus and method for forming a HSG silicon layer on a capacitor lower electrode of a semiconductor memory device. The apparatus includes a processing chamber having a plurality of source gas supply nozzles, the lengths of the nozzles being different from one another so as to uniformly supply a source gas. A loadlock chamber is placed under the processing chamber. A boat loaded with wafers is moved from the loadlock chamber to the processing chamber, with the boat being rotated while the source gas is supplied. The processing chamber and loadlock chambers are connected to a vacuum system having two vacuum pumps for maintaining a vacuum in the chambers. A third vacuum pump, connected to the processing chamber, is operated when the vacuum in the processing chamber reaches a predetermined value.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus and method formanufacturing semiconductor devices. More particularly, the presentinvention relates to an apparatus and method for manufacturingsemiconductor devices having hemispherical grains (HSG) on the lowerelectrode of the capacitor of a semiconductor memory device.

[0003] 2. Description of the Related Art

[0004] Semiconductor memory devices are becoming more highly integratedas developments progress from the 16M and 64M DRAM (Dynamic RandomAccess Memory) devices, to the 256M and greater capacity memory devices.Even as the sophistication and capacity of the device itself increases,there are ongoing efforts to keep the devices as small as possible forsubsequent implementation in miniature electronic products. In view ofthis desire to obtain smaller devices, the space for each memory cellmust be reduced accordingly.

[0005] Generally, each memory cell unit of a DRAM is composed of a MOS(Metal Oxide Semiconductor) transistor and a capacitor. Even with thereduced cell size as described above, the memory device must still havea sufficient minimum threshold capacitance in order to functionproperly.

[0006] A semiconductor capacitor includes a lower electrode (storageelectrode) and an upper electrode (plate electrode), with a dielectricmaterial between the two electrodes. The capacitance of the capacitor isproportional to the effective area of the electrodes and inverselyproportional to the distance between the two electrodes, i.e., thethickness of the dielectric. Therefore, in order to increasecapacitance, it is necessary to increase the effective capacitor areaand/or decrease the thickness of the dielectric. Also, it isadvantageous to have a dielectric with a high permittivity or dielectricconstant.

[0007] Various methods have been proposed to provide a capacitance abovea certain minimum threshold level. One such method of increasing thesurface area of the semiconductor capacitor is to use the properties ofmaterial itself, for example, by forming the lower electrode of thecapacitor with a HSG silicon layer. Such a technique is disclosed in H.Watanabe et al., “Hemispherical Grained Silicon Formation on In-SituPhosphorous Doped Amorphous-Si Using The Seeding Method”, SSDM '92 pp422-424.

[0008] Briefly, the lower electrode of the DRAM capacitor is the partthat stores information via electrons which are transferred throughcontact holes from a source area of MOS transistor. The lower electrodeis formed on the semiconductor substrate, with an intermediateinsulating film formed between the lower electrode and the substrate. Asilicon oxide film is generally used as the intermediate insulatingfilm.

[0009] The lower electrode is formed using, for example,phosphorous-doped amorphous silicon by low pressure chemical vapordeposition (CVD) techniques. After forming the lower electrode and theintermediate insulating film over the substrate, a lower electrodepattern is formed using conventional photolithography techniques know tothose skilled in the art. Thereafter, the HSG silicon layer is formedover the exposed surface of the lower electrode pattern. The HSG siliconlayer increases the surface area of the capacitor by relying on the factthat a hemisphere-shaped area is formed at the transition temperatureranges of crystalline-Si and amorphous-Si by silicon migration, with itssurface energy being stable. The HSG forming method also relies on thefact that silicon gas groups, such as Si₂H₆ and SiH₄, have reactivesurfaces, and that inner portions of the silicon layer form protrusionsthat serve as a seed for particles deposited during the CVD process,making the wafer surface rough. This roughened surface increases theeffective surface area of the electrode which thereby increases thecapacitance of the capacitor.

[0010] In the conventional process for forming a HSG silicon layer, atemperature stabilization step maintains a constant temperature, forexample, 580° C., inside a CVD apparatus having a high vacuum state. Ina subsequent seeding step, a seeding gas comprised of molecules of Si₂H₆or SiH₄ are irradiated on the surface of the exposed lower electrode,with the molecules exhibiting active surface reactions. Next, thermaltreatment is carried out to form the HSG silicon layer. The surface ofthe HSG layer is thus characterized by concave and convex hemisphericalshapes due to the thermal migration of silicon particles.

[0011] During manufacturing of a capacitor as described above, two kindsof loading methods for the wafer substrates are utilized. The firstmethod is a single wafer loading method, in which each wafer to beprocessed is moved one by one. The second method is a batch type loadingmethod, in which dozens of wafers are simultaneously moved. Although theformer method is good for maintaining uniform processing conditions, itresults in poor productivity. Thus, the latter batch type method ispreferred since productivity is enhanced.

[0012] However, batch type loading is problematic because the particularprocessing conditions experienced by the wafers vary slightly due to thedifferent positions of the wafers inside the processing chamber.Therefore, it is important to try and maintain uniform processingconditions across the entire wafer batch.

[0013]FIG. 1 is a schematic representation of a conventionalsemiconductor device fabrication apparatus incorporating a vertical lowpressure chemical vapor deposition apparatus for use in the HSGformation process.

[0014] As shown in FIG. 1, a processing chamber 20 is vertically alignedwith and disposed above a loadlock chamber 10. A gate valve 14 isinstalled between the processing chamber 20 and the loadlock chamber 10,and a boat 12 with wafers loaded thereon is placed inside the loadlockchamber 10.

[0015] The processing chamber 20 has a double tube structure, that is,an outer tube 26 being dome-shaped, with its top end sealed, covering aninner tube 24 with its top end open. A single gas supply nozzle 22 isdisposed in the inner tube 24 and supplies a source gas through anopening in a flange 16 connecting the processing chamber 20 and theloadlock chamber 10.

[0016] The gas supply nozzle 22 includes a plurality of spray openings23, spaced at equal intervals from each other. A heat block 28 encasesthe outer tube 26.

[0017] A vacuum system is installed to maintain the loadlock chamber 10and the processing chamber 20 under vacuum. The vacuum system includes aloadlock chamber vacuum line 43, having an air valve 36, connected to alower part of the loadlock chamber 10. The loadlock chamber vacuum line43 is configured to discharge through the mechanical booster pump 30 anddry pump 32. The vacuum system also includes a processing chamber vacuumline 44, having an air valve 34, which is connected to the processingchamber 60 and is also configured to discharge through the mechanicalbooster pump 30 and dry pump 32.

[0018]FIG. 2 is a detailed representation of the vacuum system for theapparatus shown in FIG. 1. The processing chamber vacuum line 44contains a bypass vacuum line, having an air valve 35 and a hand valve33 installed thereon, connected on either side of the air valve 34. Apurge gas supply line having flow meters 37 and 38, a check valve 41,and an air valve 40 are installed in order to clean mechanical boosterpump 30 and dry pump 32. Another bypass line having an air valve 39 anda check valve 42 installed thereon, is oriented so as to bypass themechanical booster pump 30 and the dry pump 32. A pirani gauge 45 formeasuring pressure is installed before the mechanical booster pump 30.

[0019] Referring to FIG. 1 and FIG. 2, in the conventional HSG siliconformation process, a boat 12 loaded with wafers, each having a lowerelectrode thereon, is moved into the loadlock chamber 10 through theside wall of the loadlock chamber 10 by a wafer transportation means.Thereafter, contaminants and native oxide films are prevented fromforming on the wafers by operating the vacuum line of the loadlockchamber 10 so as to maintain the loadlock chamber 10 under a nitrogenatmosphere in a high pressure or in a vacuum state. Then, gate valve 14is opened, and boat 12 is transferred into the processing chamber 20 byan elevator (not shown).

[0020] After stabilizing the temperature of the processing chamber, thetemperature of the processing chamber 20 is increased up to a designatedlevel in order to maximize HSG nucleus generating conditions. Thesilicon group gas is supplied as seeding gas through the gas supplynozzle 22, and the thermal treatment for nuclei growth is performed byoperating the processing chamber vacuum line so as to maintain theprocessing chamber in a high vacuum state.

[0021] After the HSG silicon layer is formed on the lower electrode ofthe capacitor, the boat 12 is moved back to the loadlock chamber 10 forcooling, and the process is complete.

[0022] The above conventional apparatus for manufacturing semiconductordevices using batch-type loading has good productivity, but theprocessing conditions are different throughout every position of thewafers inside the boat such that the processing results are not uniformthroughout the wafers in the same batch. Also, for HSG nucleus growth,it takes too long a time to reach the desired vacuum state inside theprocessing chamber 20, so that silicon migration is difficult and thesize of the hemispherical silicon nucleus is reduced.

SUMMARY OF THE INVENTION

[0023] The present invention is directed to an apparatus which providesfor the formation of a uniform film throughout each of a plurality ofwafers placed in the same batch during the semiconductor devicefabrication process.

[0024] Another object of the present invention is to provide anapparatus for manufacturing semiconductor devices which provides for theready formation of HSG silicon nuclei having a predetermined density andsize, on the lower electrode of the capacitor.

[0025] A further object of the present invention is to provide a methodfor manufacturing semiconductor devices using the above apparatusaccording to the present invention.

[0026] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly described, theapparatus for manufacturing semiconductor devices, includes: aprocessing chamber; a loadlock chamber disposed under the processingchamber; a vacuum system connected to the processing chamber and theloadlock chamber; and a plurality of gas supply nozzles placed insidethe processing chamber, each of the gas supply nozzles having adifferent length from each other, and having a plurality of sprayopenings vertically aligned at uniform intervals for spraying a sourcegas uniformly throughout the inside of the processing chamber.

[0027] The plurality of supply nozzles are installed along the bottom ofthe processing chamber, and they can be oriented in close proximity toeach other, or spaced apart in equal intervals along the bottom of theprocessing chamber.

[0028] The gas supply nozzles include a first supply nozzle forsupplying a source gas to an upper area of the processing chamber, asecond supply nozzle for supplying a source gas to a middle area of theprocessing chamber, processing chamber, with all of the supply nozzlesbeing vertically aligned with respect to one another. Preferably, thetop ends of the first and second supply nozzles are sealed, and thebottom end of the third supply nozzle is open.

[0029] More preferably, the diameter of the spray openings of the gassupply nozzles would increase the closer the spray opening is to theterminal end of the nozzle (upper end). Each of the gas supply nozzlesmay branch of a single supply line connected to a single source gassupply. Alternatively, each nozzle may have its own dedicated supplyline connected to a different respective source gas supply, forsupplying one or more types of source gas to the chamber if required ordesired.

[0030] According to a second embodiment of the present invention, thereis provided an apparatus for transporting wafers in a boat between theprocessing chamber and the loadlock chamber. The transporting apparatusincludes an elevator for reciprocally moving the boat between theprocessing chamber and the loadlock chamber, and rotating a apparatusfor rotating the boat when in the processing chamber.

[0031] The rotating apparatus includes a boat support for mounting theboat thereon, a motor for rotating the boat support about a motor shaftaxis, and a controller for controlling the rotation speed of the boat.The rotating apparatus rotates the boat after it is moved into theprocessing chamber to ensure uniform processing of the wafers.

[0032] According to a third embodiment of the present invention, thevacuum system includes a loadlock line having one end connected to theloadlock chamber and a processing line having one end connected to theprocessing chamber. Both the loadlock and the processing lines merge ata first junction prior to passing through a first vacuum pump and asecond vacuum pump. A bypass vacuum line originating from the processingline passes through a third vacuum pump, and then merges again with theprocessing line at a point between the first junction and the firstvacuum pump.

[0033] The first, second, and third vacuum pumps are a mechanicalbooster pump, a dry pump, and a turbo molecular pump respectively, andpreferably, purge gas supply and discharge lines are installed in orderto clean the inside of the third vacuum pump.

[0034] The inside of the processing vacuum line and the bypass vacuumline are polished so as to maximize the vacuum state. A heating means isinstalled along portions of the processing line and bypass line betweenthe third vacuum pump and the processing chamber, to minimizing thebyproduct produced after the processing is completed.

[0035] A nitrogen gas supply line and an oxygen gas supply line areinstalled in the loadlock chamber to remove contaminants and control theformation of native oxide films.

[0036] In another aspect, the present invention provides a method forproducing semiconductor devices using the above apparatus. The methodincludes loading wafers to be processed into a wafer boat, maintainingthe loadlock chamber in a vacuum state by operating the first and secondvacuum pumps of the loadlock chamber vacuum system, moving the waferboat from the loadlock chamber to the processing chamber, processing thewafers by supplying a source gas into the processing chamber whileoperating the first and second vacuum pumps to maintain the processingchamber vacuum; and operating the third vacuum pump of the bypass vacuumline when the pressure of the processing chamber reaches a certainpredetermined value. The third vacuum pump of the bypass vacuum line isoperated to reach a base vacuum state quickly during the step of growingthe HSG nuclei, so as to maximize silicon migration.

[0037] After the wafer boat moves into the processing chamber, the waferboat is then rotated to achieve uniform processing. A source gas isuniformly supplied from the gas supply nozzles throughout the inside ofthe processing chamber, such that the HSG silicon layers are uniformlyformed on the lower electrodes of wafers by rotation of the wafer boatduring processing.

[0038] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In the accompanying drawings:

[0040]FIG. 1 is a schematic representation of a conventional apparatusfor manufacturing semiconductor devices;

[0041]FIG. 2 is a detailed schematic representation of the vacuum systemof the apparatus shown in FIG. 1;

[0042]FIG. 3 is a schematic representation of the apparatus formanufacturing semiconductor devices according to an embodiment of thepresent invention;

[0043]FIG. 4 is an enlarged perspective view of the source gas supplyportion of the apparatus shown in FIG. 3;

[0044]FIG. 5 is a side view of the rotating apparatus of the presentinvention for rotating the wafer boat; and

[0045]FIG. 6 is a detailed schematic representation of the vacuum systemof the apparatus shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] The present invention now will be described more fullyhereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown.

[0047]FIG. 3 is a schematic representation of the apparatus formanufacturing semiconductor devices for the formation of HSG accordingto one embodiment of the present invention. The vertically alignedprocessing chamber 60 and loadlock chamber 50 are coupled by flange 56.A gate valve 54 is installed between the processing chamber 60 and theloadlock chamber 50 to separate the two chambers.

[0048] The processing chamber 60 has a double-tube structure, that is,an outer tube 66 with a dome-shaped sealed top covering an inner tube 64with its top end opened. A heat block 68 covers the outer tube 66.

[0049] A plurality of gas supply nozzles 62 are vertically installedinside inner tube 64 to supply a source gas from a source gas supply 112to the interior of the inner tube 64, through a supply line 111 whichpenetrates through the side wall of flange 56 and into the inner tube64. The outer tube 66 and the inner tube 64 are made of quartz and/orSiC.

[0050]FIG. 4 is an enlarged perspective view of the gas supply nozzles62 shown in FIG. 3. Referring to FIG. 3 and FIG. 4, a plurality of gassupply nozzles 62 are installed inside the inner tube 64, the lengths ofthe nozzles each being different from one another. That is, a firstsupply nozzle 62 a is for example, the tallest to supply the source gasto an upper area of the processing chamber 60, a second supply nozzle 62b and a third supply nozzle 62 c are installed to supply the source gasfor example, to a middle area and a lower area of the processing chamber60, respectively. The top terminal ends of the first and second supplynozzles 62 a and 62 b are preferably sealed, and on their upper ends,spray openings 62 a′ and 62 b′ are formed, preferably three, with theopenings having diameters different from each other, and being alignedat uniform intervals. The diameters of the spray openings 62 a′ and 62b′ closer to top end of the supply nozzles are larger so that a sourcegas is uniformly supplied throughout the inside of the processingchamber 60. The end of the third supply nozzle 62 c is preferably openso that the source gas is sprayed directly toward the lower area of theprocessing chamber 60.

[0051] While this embodiment preferably includes three gas supplynozzles, any number and shape of gas supply nozzles installed at anyinterval along the boundary line of the processing chamber 60, arecontemplated provided that the number, size and location of the nozzlesare sufficient to uniformly supply source gas to the interior of theinner chamber 64.

[0052] The number, height and distribution of nozzles can be readilyselected and employed by one of ordinary skill in the art without undueexperimentation depending upon the particular application and desiredresults. The location and the size of the spray openings of each supplynozzle are important parameters for controlling the density and the sizeof HSG nuclei. The location and size of the openings vary according tothe particular application. The location and size can be determined,optimized and employed by one of ordinary skill in the art without undueexperimentation.

[0053] As seen in FIG. 4, three spray openings 62 a′ of the first supplynozzle 62 a are formed on its upper end to supply a source gas to theupper quarter of the wafers in boat 52, those spray openings 62 b′ ofthe second supply nozzles 62 b providing gas to the middle one-half ofthe wafers, and the third supply nozzle 62 c providing gas to the lowerquarter of the wafers in boat 52 in the processing chamber. Preferably,each nozzle is made of quartz or SiC with about a ¼ inch diameter inorder to prevent contaminants during the processing.

[0054] The first, second, and third gas supply nozzles 62 a, 62 b, 62 cmay branch of a single supply line 111 connected to a single source gassupply 112 as shown in FIG. 3. Alternatively, each nozzle 62 a, 62 b, 62c may have its own dedicated supply line 62 a″, 62 b″, 62 c″ connectedto a respective source gas supply 62 a′″, 62 b′″, 62 c′″, for supplyingone or more types of source gas to the chamber. The source gas isselected from a silicon group gas, such as SiH₄ or Si₂H₆, for formingHSG.

[0055]FIG. 5 is a detailed representation showing the rotating apparatus100 of the loadlock chamber 50 of FIG. 3. Referring to FIG. 5, the boat52, placed on horizontal boat support 53, is vertically moved up anddown by elevator 58 so that boat flange 51 moves towards the processingchamber 60 when the gate valve 54 opens. After the boat 52 istransferred to the processing chamber 60, the gate valve 54 is closed.Then, during wafer processing, the horizontal boat support 53 rotatesboat 52 by the driving force of motor 55 transferred via the rotatingshaft 57 connected to the boat support 53. The rotation speed of motor55 is controlled by a controller 56 in motor 55. The rotating shaft 57is covered with a bellows 59 to prevent the accumulation of thecontaminants generated by any abrasion caused by rotation of therotating shaft 57.

[0056] A nitrogen gas supply line (not shown) and an oxygen gas supplyline (not shown) are preferably installed in the loadlock chamber toremove contaminants and control the formation of native oxide films.

[0057]FIG. 6 is a detailed representation of the vacuum system of FIG.3. The vacuum system maintains the processing chamber 60 and theloadlock chamber 50 at a particular pressure. As shown in FIG. 3 andFIG. 6, the vacuum system includes a loadlock line 83, having an airvalve 76, one end of which is connected to the lower end of the loadlockchamber 50. A processing line 84, having an air valve 74, has one endconnected to the lower end of the outer tube 66 of the processingchamber. Loadlock line 83 and processing line 84 merge just prior to afirst vacuum pump 70, and then pass through the first vacuum pump 70 anda second vacuum pump 72.

[0058] A first bypass vacuum line 110, having air valves 88 and 89,branches from the processing line 84 near the outer tube 66 and passesthrough a third vacuum pump 86. The air valves 88 and 89 are located oneither side of the third vacuum pump 86. The bypass vacuum line 110 alsoleads to the first vacuum pump 70. As shown in FIG. 6, the bypass vacuumline 110 merges with the processing line 84 at a point downstream of themerge point of the loadlock line 83 and processing line 84, and prior toentering the first vacuum pump 70.

[0059] Just after the point where the first bypass vacuum line 110branches from the processing line 84, a second bypass line 112, havingair valve 75 and hand valve 73, is connected to the processing line 84on either side of an air valve 74.

[0060] The first 70, second 72, and third 86 vacuum pumps are amechanical booster pump (MBP), a dry pump (DP), and a turbo molecularpump (TMP), respectively. The booster pump and dry pump are rough orlower vacuum pumps with a pressure range of from 760 torr to 1×0-3 torr.The pumps may be, for example, a piston rotation pump, an oil rotationpump, or a venturi pump.

[0061] The turbo molecular pump is high vacuum pump with a pressurerange of from 1×10⁻³ torr to 1×10⁻⁸ torr. This pump may be, for example,an oil diffusion pump, a cryo trap and baffle pump, or a mechanical cryopump. The turbo molecular pump is a clean mechanical pressure pump thatprovides momentum and direction to the gas molecules, is free fromvibration because it employs a high speed rotation surface, and is usedbecause it reaches a vacuum state in a short time at pressures less than5×10⁻¹⁰ torr.

[0062] The vacuum lines in the vacuum system are preferably made ofstainless steel and polished to maximize the vacuum capability. Also, asshown in FIG. 3, heating tape 87 (i.e., a polymeric tape having aheating coil disposed therein) is installed in order to heat the portionof the vacuum system between the third vacuum pump 86 of the bypass line110 to the outer tube 66 of the processing chamber 60, and between theair valve 74 (along the processing line 84) and the outer tube 66 of theprocessing chamber 60, so as to minimize the generation of waste gas andparticle byproducts after processing is completed. The heating tape 87is preferably maintained at a temperature of from 50° C. to 200° C.

[0063] The mechanical booster pump 70 and the dry pump 72 are cleanedusing purge gas supplied through purge gas supply lines 114 and 116.Purge gas supply line 114 includes flow meter 77 installed thereon, andpurge gas supply line 116 includes flow meter 78, a check valve 81, andan air valve 80, installed thereon. A third bypass line 118, having anair valve 79 and a check valve 82, is installed so as to bypass themechanical booster pump 70 and the dry pump 72. A pressure measuringpirani gauge 85 is installed near the junction point of the processingline 84 and the loadlock line 83, before the mechanical booster pump 70.

[0064] At a point along the first bypass line 110, and between the thirdvacuum pump 86 and the first vacuum pump 70, a forth bypass line 120,having air valve 95 and a check valve 98, branches from the first bypassline 110 and bypasses the mechanical booster pump 70 and a dry pump 72.

[0065] Purge gas supply and discharge lines 122 and 124 are installed inorder to clean the turbo molecular, pump 86 with for example, nitrogengas. The purge gas supply line 122 originates from a purge gas supply(not shown), passes through a flow meter 93, a check valve 92, and anair valve 90, and is connected to the first bypass line 110 between theturbo molecular pump 86 and air valve 88. Purge gas discharge line 124originates from the turbo molecular pump 86, passes through air valve 91and flow meter 94, and converges with purge gas supply line 122, withthe converging lines being connected to the purge gas supply.

[0066] A pressure switch 96 and a pirani gauge 97 are installed on thefirst bypass line 110, in-line and downstream of turbo molecular pump86. An ion gauge 99 is installed close to the processing chamber 60 onthe processing line 84.

[0067] With reference to FIGS. 3 to 6, the vacuum system beingsoperating by first closing the air valves 74 and 89 connected to theprocessing chamber 60, and air valve 76 connected to the loadlockchamber 50, so as to maintain the loadlock chamber 50 and processingchamber 60 in a vacuum state when mechanical booster pump 70 and drypump 72 begin to operate.

[0068] When the pressure of the processing chamber 60 reaches a certainpredetermined value, e.g., 4 Pascal (i.e., 3×10⁻² Torr), the firstbypass vacuum line 110 automatically opens and air valve 74 closes. Thatis, air valves 88 and 89 are opened while the turbo molecular pump 86operates to reach a base vacuum in a short time.

[0069] Then, wafers having patterned lower electrodes are loaded ontoboat 52 in the loadlock chamber 50 while the nitrogen gas supply lineremoves contaminants from the chamber and the oxygen gas supply linecontrols the formation of native oxide films. Subsequently, the boat 52is moved from the loadlock chamber 50 to the processing chamber 60 viathe elevator 58 after the gate valve 54 is opened. The boat 52 is thenrotated by the motor 55 connected to the boat support 53 via the motorshaft 57. While the boat 52 is rotated, source gas for forming HSG issupplied to the processing chamber 60 via the plurality of nozzles 62 a,62 b, 62 c in order to uniformly process the wafers in the boat 52.

[0070] More specifically, the complete fabrication process includesstand-by, temperature ramp-up, HSG seeding and HSG growth steps.

[0071] The formation of native oxide films is prevented during thestand-by step by maintaining the processing chamber 60 at a temperaturein the range of from 450° C. to 500° C. without oxygen. During thetemperature ramp-up step, the temperature is increased from the 450° C.to 500° C. range, preferably to about 550° C. in order to maximizesuitable seeding conditions. During this temperature ramp-up step, oneshould avoid overshooting a temperature of a certain value, for example550° C.

[0072] During the seeding step, a seeding gas such as SiH₄ or Si₂H₆ issupplied from the gas supply nozzles 62 to the processing chamber 60 soas to form HSG nuclei on the lower electrode.

[0073] The growth step includes thermally treating the wafers at atemperature greater than 550° C., to grow the HSG nucleus. The uppertemperature limit of the HSG growth step is approximately 800° C. Atthis time, the first, and second vacuum pumps 70 and 72 are operated tomaintain a high vacuum state, and when the pressure of the processingchamber 60 reaches a specific predetermined value, e.g., 4 Pa., thethird vacuum pump 86 is operated.

[0074] After the HSG silicon nucleus has sufficiently grown on the lowerelectrode and the processing is complete, gate valve 54 is opened andthe boat 52 is lowered from the processing chamber 60 back into theloadlock chamber 50. The wafers are then cooled at a constanttemperature and moved out of loadlock chamber 50.

[0075] According to the present invention, the formation of uniformfilms is achieved regardless of the location of the wafers in a singlebatch, by for example, uniformly suppling a source gas, and by rotatingthe boat during the processing operation.

[0076] Furthermore, by adding a high vacuum pump to the vacuum system ofthe present invention, the required vacuum state is achieved in ashorter time so that the density and the size of HSG nuclei are uniform,and result in an increased effective surface area of the capacitor, andthereby, an improved capacitance of the capacitor.

[0077] While the present invention has been described in detail, itshould be understood that various changes, substitutions and alterationscan be made hereto without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. An apparatus for manufacturing semiconductordevices, comprising: a processing chamber for processing semiconductorwafers; a loadlock chamber vertically aligned with and disposed undersaid processing chamber; a vacuum system connected to said processingchamber and said loadlock chamber; and a plurality of gas supply nozzlesin flow communication with said processing chamber, each of said gassupply nozzles having a length different from each other, and designatedones of said gas supply nozzles having a plurality of spaced apart sprayopenings for uniformly spraying a source gas throughout interior areasof said processing chamber.
 2. The apparatus of claim 1, said processingchamber comprising an inner tube having an open top end, said inner tubedisposed inside a sealed outer tube, and wherein said gas supply nozzlesare disposed along a bottom portion of said processing chamber.
 3. Theapparatus of claim 2, said gas supply nozzles comprising: a first supplynozzle extending vertically within said processing chamber and havingvertically spaced spray openings for supplying said source gas to anupper interior area of said processing chamber; a second supply nozzleextending vertically within said processing chamber to a height lessthan said first supply nozzle, and having vertically spaced sprayopenings for supplying said source gas to a middle interior area of saidprocessing chamber; and a third supply nozzle extending laterally withinsaid processing chamber for supplying said source gas to a lowerinterior area of said processing chamber.
 4. The apparatus of claim 3,wherein a top terminal end of said first supply nozzle and of secondsupply nozzle, are sealed, and a terminal end of said third supplynozzle is open.
 5. The apparatus of claim 4, wherein diameters of saidspray openings of said first and second gas supply nozzles increase assaid openings approach the top terminal ends of said first and secondgas supply nozzles.
 6. The apparatus of claim 5, wherein each of saidgas supply nozzles branch off a single supply line connected to a singlesource gas supply.
 7. The apparatus of claim 5, wherein each of said gassupply nozzles is separately connected to a separate source gas supply.8. An apparatus for manufacturing semiconductor devices, comprising: aprocessing chamber for processing semiconductor wafers; a loadlockchamber vertically aligned with and disposed under said processingchamber; a vacuum system connected to said processing chamber and saidloadlock chamber; an elevator for vertically moving said wafers betweensaid processing chamber and said loadlock chamber; and a rotatingapparatus for rotating said wafers in said processing chamber.
 9. Theapparatus of claim 8, wherein said wafers are placed in a wafer boat andsaid rotating apparatus comprises means for controlling a rotation speedof said wafer boat.
 10. The apparatus of claim 9, said rotatingapparatus further comprising a horizontal boat support for mounting saidwafer boat thereon, and a motor connected to said boat support via arotating shaft for rotating said boat support.
 11. The apparatus ofclaim 10, further comprising a bellows surrounding said rotating shaft.12. An apparatus for manufacturing semiconductor devices, comprising: aprocessing chamber for processing semiconductor wafers; a loadlockchamber vertically aligned with and disposed under said processingchamber; a vacuum system connected to said processing chamber and saidloadlock chamber, said vacuum system comprising, a first vacuum pump anda second vacuum pump, a loadlock line having one end connected to saidloadlock chamber, a processing line having one end connected to saidprocessing chamber, wherein said loadlock line and said processing linemerge at a first junction along said processing line before passingthrough the first vacuum pump and the second vacuum pump; and a bypassline branching off said processing line upstream of said first junction,said bypass line passing through a third vacuum pump and merging at asecond junction along said processing line, said second junction beingat a point between said first junction and said first vacuum pump. 13.The apparatus of claim 12, wherein said first, second, and third vacuumpumps comprise a mechanical booster pump, a dry pump, and a turbomolecular pump, respectively.
 14. The apparatus of claim 13, furthercomprising purge gas supply and discharge lines connected to said thirdvacuum pump and a purge gas supply.
 15. The apparatus of claim 14,further comprising a second bypass line branching from said bypass linebetween said third vacuum pump and said second junction and bypassingsaid first and second vacuum pumps.
 16. The apparatus of claim 15,further comprising an ion gauge installed along said processing linebetween said processing chamber and a point where said bypass linebranches from said processing line.
 17. The apparatus of claim 12,wherein said processing line and said bypass line are made of stainlesssteel.
 18. The apparatus of claim 17, wherein an interior surface ofsaid processing line and said bypass line are polished.
 19. Theapparatus of claim 12, further comprising heating means installed aroundselected portions of said vacuum system, said selected portions being atleast between said third vacuum pump of said bypass line to saidprocessing chamber.
 20. The apparatus of claim 19, wherein a temperatureof said heating means is controlled within a range of from 50° C. to200° C.
 21. An apparatus for manufacturing semiconductor devices,comprising: a processing chamber for processing semiconductor wafers; aloadlock chamber vertically aligned with and disposed under saidprocessing chamber; a plurality of gas supply nozzles in flowcommunication with said processing chamber, each of said gas supplynozzles having a length different from each other, and designated onesof said gas supply nozzles having a plurality of spaced apart sprayopenings for uniformly spraying a source gas throughout interior areasof said processing chamber; an elevator for vertically moving saidwafers between said processing chamber and said loadlock chamber; arotating apparatus for rotating said wafers in said processing chamber;and a vacuum system connected to said processing chamber and saidloadlock chamber, said vacuum system comprising, a first vacuum pump anda second vacuum pump, a loadlock line having one end connected to saidloadlock chamber, a processing line having one end connected to saidprocessing chamber, wherein said loadlock line and said processing linemerge at a first junction along said processing line before passingthrough the first vacuum pump and the second vacuum pump; and a bypassline branching off said processing line upstream of said first junction,said bypass line passing through a third vacuum pump and merging at asecond junction along said processing line, said second junction beingat a point between said first junction and said first vacuum pump. 22.The apparatus of claim 21, said gas supply nozzles comprising: a firstsupply nozzle extending vertically within said processing chamber andhaving vertically spaced spray openings for supplying said source gas toan upper interior area of said processing chamber; a second supplynozzle extending vertically within said processing chamber to a heightless than said first supply nozzle, and having vertically spaced sprayopenings for supplying said source gas to a middle interior area of saidprocessing chamber; and a third supply nozzle extending laterally withinsaid processing chamber for supplying said source gas to a lowerinterior area of said processing chamber.
 23. The apparatus of claim 22,wherein a top terminal end of said first supply nozzle and of secondsupply nozzle, are sealed, and a terminal end of said third supplynozzle is open.
 24. The apparatus of claim 23, wherein diameters of saidspray openings of said first and second gas supply nozzles increase assaid openings approach the top terminal ends of said first and secondgas supply nozzles.
 25. The apparatus of claim 24, wherein said wafersare placed in a wafer boat and said rotating apparatus comprises meansfor controlling a rotation speed of said wafer-boat.
 26. The apparatusof claim 25, said rotating apparatus further comprising a horizontalboat support for mounting said wafer boat thereon, and a motor connectedto said boat support via a rotating shaft for rotating said boatsupport.
 27. The apparatus of claim 26, wherein said first, second, andthird vacuum pumps comprise a mechanical booster pump, a dry pump, and aturbo molecular pump, respectively.
 28. The apparatus of claim 27,further comprising purge gas supply and discharge lines connected tosaid third vacuum pump and a purge gas supply.
 29. The apparatus ofclaim 28, further comprising a second bypass line branching from saidbypass line between said third vacuum pump and said second junction andbypassing said first and second vacuum pumps.
 30. The apparatus of claim29, further comprising heating means installed around selected portionsof said vacuum system, said selected portions being at least betweensaid third vacuum pump of said bypass line to said processing chamber.31. The apparatus of claim 30, further comprising a nitrogen gas supplyline and an oxygen gas supply line installed in said loadlock chamber.32. A method for manufacturing semiconductor devices, comprising:stacking wafers to be processed into a wafer boat; maintaining aninterior of a loadlock chamber in a vacuum state by operating first andsecond vacuum pumps, said first and second vacuum pumps being connectedto said loadlock chamber and a processing chamber arranged above saidloadlock chamber; moving said wafer boat from said loadlock chamber tosaid processing chamber; supplying a source gas into said processingchamber to process said wafers; operating said first and second vacuumpumps to maintain a vacuum in said processing chamber; and operating athird vacuum pump connected to said processing chamber when the vacuumin said processing chamber reaches a predetermined value.
 33. The methodof claim 32, said step of supplying comprising a step of simultaneouslyrotating said wafer boat in said processing chamber while supplying saidsource gas.
 34. The method of claim 33, wherein said operating a thirdvacuum pump step commences when said predetermined value is about 4pascal.
 35. A method for manufacturing semiconductor devices,comprising: maintaining a plurality of wafers loaded in a boat, in achamber under a first predetermined vacuum pressure at a firstpredetermined temperature, wherein said wafers comprise a plurality ofpatterned lower electrodes; raising said first predetermined temperaturein said chamber to a greater, second predetermined temperature;supplying a silicon source gas to an interior of said chamber containingsaid wafers; and reducing pressure in said chamber to a secondpredetermined vacuum pressure less than said first predeterminedpressure, under conditions effective to produce semiconductor deviceseach having HSG silicon nuclei formed on a patterned lower electrode ofa capacitor of each of said semiconductor devices.
 36. The method ofclaim 35, said step of supplying further comprising a step of rotatingsaid boat in said processing chamber while supplying said silicon sourcegas in said supplying step.
 37. The method of claim 36, wherein saidfirst predetermined temperature is from 450° C. to 500° C.
 38. Themethod of claim 37, wherein said second predetermined temperature isgreater than 550° C.
 39. The method of claim 38, wherein said firstpredetermined pressure is from 760 torr to 1×10⁻³ torr and said secondpredetermined pressure is from 1×10⁻³ torr to 1×10⁻⁸ torr.
 40. Themethod of claim 39, wherein said silicon source gas is selected from thegroup consisting of Si₂H₆ and SiH₄.